The quantitative determination of analytes in body fluids is of great importance in the diagnoses and maintenance of certain physiological abnormalities. For example, lactate, cholesterol and bilirubin should be monitored in certain individuals. In particular, it is important that diabetic individuals frequently check the glucose level in their body fluids to regulate the glucose intake in their diets. The results of such tests can be used to determine what, if any, insulin or other medication needs to be administered. In one type of blood-glucose testing system, sensors are used to test a sample of blood.
A test sensor contains biosensing or reagent material that reacts with blood glucose. The testing end of the sensor is adapted to be placed into the fluid being tested, for example, blood that has accumulated on a person's finger after the finger has been pricked. The fluid is drawn into a capillary channel that extends in the sensor from the testing end to the reagent material by capillary action so that a sufficient amount of fluid to be tested is drawn into the sensor. The fluid then chemically reacts with the reagent material in the sensor resulting in an electrical signal indicative of the glucose level in the fluid being tested. This signal is supplied to the meter via contact areas located near the rear or contact end of the sensor and becomes the measured output.
One existing process for forming an electrochemical sensor is to deposit a conductive metal onto a substrate and then use a subtractive method for removing selected portions of the deposited conductive metal. Another existing process is to print the electrode by using a conductive ink, which is an additive process. The conductive ink may contain platinized carbon, platinum or other noble metal with a carrier that includes carbon particles. In both of these existing processes, the area of the conductive metal that can be used as an electrode is limited to a single two-dimensional footprint. Since the conductive material is expensive, it is desirable for the manufacturer to use as little conductive material as necessary while still maintaining the desired functionality.
It would be desirable to have an electrochemical sensor system that reduces the amount of conductive material needed, which reduces the cost, while at the same time still maintaining the desired functionality.